Various operation input devices have been used with an information processing apparatus, such as a notebook-sized computer. For example, a keyboard having keys corresponding to the alphabet, numbers, and symbols has been used. Additionally, a touch panel which can be operated when a user touches the panel with a finger or the like has also been used with the information processing apparatus.
When a user touches the touch panel with a finger or the like, it is possible to change a display position of a pointer displayed on a screen of the information processing apparatus. A plurality of electrodes may be embedded in an operation surface of the touch panel and a touched position may be determined by detecting electrostatic capacity changes between the electrodes when the user touches the operation surface with the finger or the like.
Alternatively, an operation input device different from the touch panel may be used with the information processing apparatus. For example, an operation input device called a “pen tablet” may be used. In this case, a user touches an operation surface with a pen-shaped input device (stylus) designed for use with the pen tablet so that a user is able to perform an input operation which corresponds to the position touched with the stylus.
The pen tablet may be an electromagnetic induction type pen tablet in which a plurality of loop coils are embedded in an operation surface and a magnetic field is generated from the loop coils. The stylus which serves as a position pointing device includes coils that react with a magnetic field generated by the loop coils of the pen tablet. The electromagnetic induction type pen tablet is able to detect the position of the stylus based on an electromagnetic interaction generated between the magnetic field generated by the loop coils of the pen tablet and the stylus, when the stylus contacts or approaches the operation surface of the pen tablet.
Here, when the touch panel and the pen tablet are installed in a portable personal computer apparatus, considering the limited space and small size of the portable personal computer, respective position detecting mechanisms located under a common operation surface have been used to detect an input operation of both a finger of a user and a stylus.
Japanese Published Patent Application No. 9-1387730 describes a technology in which a detecting unit which serves as an electrostatic capacity type touch panel and a detecting unit which serves as an electromagnetic induction type pen tablet are disposed under a common operation surface.
However, when two operation input mechanisms (i.e., both detecting units) are located under the common operation surface, it becomes necessary to switch between the two operation input mechanisms. For example, when the display position of the pointer on the display screen of the personal computer apparatus is affected by these two operation input mechanisms, if it is detected that the electrostatic capacity type touch panel is also touched with the stylus when the personal computer apparatus is being operated by touching the operation surface with the stylus, then detected data from the two operation input mechanisms are both supplied to the personal computer apparatus. As a result, operation of the personal computer apparatus will be adversely affected. In particular, the pointer in the display screen may be moved erroneously.
For this reason, switch processing is used to select between the two operation input mechanisms. However, if the two operation input mechanisms are switched by using a manual switch, then operability will be reduced. Hence, the personal computer apparatus may include an automatic switching mechanism.
The Japanese Published Patent Application No. 9-1387730 describes switch processing in which, when the stylus approaches the operation surface within a certain distance, the electromagnetic induction type pen tablet is used with priority, and, in the meantime, the electrostatic capacity type touch panel is de-energized. However, this switch processing described in the Japanese Published Patent Application No. 9-1387730 describes is not able to switch the two operation input mechanisms satisfactorily.
More specifically, the switch processing described in the Japanese Published Patent Application No. 9-1387730 requires that a user should operate the stylus in constant contact with the operation surface.
However, some pen tablets can be operated in a state in which a tip of the stylus is not directly in contact with the operation surface, but instead the stylus and/or tip of the stylus is close or approaching the operation surface.
If the pen tablet can be operated by moving the tip of the stylus close to the operation surface, then a detection operation of the pen tablet to detect the approach of the tip of the stylus is used in both a switching operation and an input operation. Thus, when the pen tablet is operated with the stylus which is not in contact with the operation surface but is close to the operation surface, there is a possibility that the electromagnetic induction type pen tablet and the electrostatic capacity type touch panel will be switched unintentionally. This unintentional switching is problematic.
Also, when a display panel and the operation input device described above are formed as one body so that the personal computer apparatus may be operated by touching a display surface with a finger or stylus, operability of the personal computer apparatus can be improved. However, if the touch panel type operation input device described above and the pen tablet type operation input device described above are attached to the same display panel, then a problem arises in that switch processing to switch the above two operation input devices is required.
While a problem arising when the electrostatic capacity type touch panel and the electromagnetic induction type pen tablet are located at the same position has been described above, a similar problem also arises when two types of detecting units with other types of operation input mechanisms are disposed at the same place. Accordingly, there is a need for improved switch processing used to switch between input mechanisms.